It's simplicity itself to modify a Bren mag catch to retain the 7.92mm magazines. Forget all the epoxy stuff (the stuiff of nightmares in my opinion.....) and silver solder a piece of metal to thje front face. Then judiciously file it carefully until...... lo and behold....., you have a 7.62mm catch!
As for the fit of the 7.92mm magazine. As told, they aren't LONGER but the extreme rear bottom edge differs. Look carefully and the Bren magazine follows a very subtle curved arc whereas the ZB doesn't. It is this curved arc that allows the Bren magazine to fit - or DOESN'T allow the ZB magazine to fit depending on your take on things. As this curvature allows you to insert the nose of the mag in place and roll the magazine rearwards (in an arc centred about the front protruding rib) to engage with the mag catch. To allow the ZB magazine to fit you must relieve the rear left and right corners of the Bren magazine well to cater for the straighter rear bottom edges of the ZB magazine.
This was a condition of the pre-war experimental trials with a .303" gun that went back to ZB to investigate the possibility of Brens being made as 7.92mm guns in the future. Mags weren't to be interchangeable. Luckily all the drawings were in hand for 7.92mm magazines when a) a LARGE amount of 7.92mm ZB guns without magazines were captured by S/African forces during a raid into
German
West African territory during the war and later, when
Canada manufactured 7.92mm guns. All done using the Enfield pre-war design.
Not a lot of people know that!
Originally Posted by 
PM
